This invention relates to a system for transferring packet data.
Packet transfer systems, where data are transferred within a wired section of communication network while being sectioned into given data-length packets each of which is provided with a destination code, are of a connectionless type that without establishing a line when calling a packet, packet data are transferred using shared channel and of a connection-oriented type that a leased channel is assigned to each user when calling a packet and then packet data are transferred using the leased channel.
FIG. 1 is an illustration showing a connectionless type packet transfer system.
As shown in FIG. 1, a communication system that the conventional connectionless type packet transfer system is applied is composed of multiple terminals 110a to 110c, a wireless base station 120 that is connected through wireless lines with the terminals 110a to 110c, and a packet switching office 130 that is connected through wired packet lines with the wireless base station 120. The packet switching office 130 is connected with a network 140, such as a packet network as a public network and PSTN as a circuit switched network. Also, in the packet switching office 130, packet terminal equipment 135 to perform a Layer 2 protocol terminal function is provided, where the other Layer 2 protocol terminal function is performed by the terminals 110a to 110c. 
In the communication system using the connectionless type packet transfer system, all the lines between the wireless base station 120 and the packet switching office 130 are used as shared channels that the multiple terminals 110a to 110c can use commonly. So, through one channel, the transferring of packet data by the terminals 110a to 110c may be performed.
FIG. 2 is an illustration showing a connection-oriented type packet transfer system.
As shown in FIG. 2, a communication system that the conventional connection-oriented type packet transfer system is applied is similar to that in FIG. 1.
In the communication system using the conventional connection-oriented type packet transfer system, when calling a packet, multiple channels between the wireless base station 120 and the packet switching office 130 are used as leased channels each of which only one of the terminals 110a to 110c can use, where the transferring of packet data by the terminals 110a to 110c can be performed using the leased channels assigned to the respective terminals 110a to 110c. 
However, in the conventional packet transfer systems, the following problems may occur.
(1) In the connectionless type packet transfer system, since one channel is used commonly by multiple users, the utilization efficiency per one channel is enhanced. However, the retransmission throughput for guaranteeing the packet data of multiple users at that channel must be reduced.
(2) In the connection-oriented type packet transfer system, since one channel is assigned to one user, the retransmission throughput at that channel is enhanced. However, since the leased channel is used exclusively by one user from calling to releasing of packet, the hard physical quantity must increase.
Also, when packet data are transferred intermittently, the leased channel will be established even when there is no data transferred. Therefore, the ineffective reserved hard resource must increase. Here, for the packet communications, the per-unit charging system (charging based on the amount of information transferred) is employed in place of the time charging system (charging based on the time during the line is used) for line switching. Therefore, in the above case, a wasteful cost will occur.
Accordingly, it is an object of the invention to provide a packet transfer system that packet data can be transferred efficiently without reducing the retransmission throughput of line and without increasing the hard physical quantity.
According to the invention, a packet transfer system for transferring data from a plurality of terminals while sectioning the data into given data-length packets, comprises:
a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly;
wherein when the amount of data transferred from one of the plurality of terminals is greater than a predetermined value, one of the shared channels is assigned exclusively to the one of the plurality of terminals and data transferred from the one of the plurality of terminals is transferred using only the one of the shared channels.
According to another aspect of the invention, a packet transfer system for transferring data to a plurality of terminals while sectioning the data into given data-length packets, comprises:
a communication system that is composed of the plurality or terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly;
wherein when the amount of data transferred to one of the plurality of terminals is greater than a predetermined value, one of the shared channels is assigned exclusively to the one of the plurality of terminals and data transferred to the one of the plurality of terminals is transferred using only the one of the shared channels.
According to another aspect of the invention, a packet transfer system for transferring data from a plurality of terminals while sectioning the data into given data-length packets, comprises:
a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a stitching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly and a leased channel that only one of the plurality of terminals can use;
wherein only when the amount of data transferred from one of the plurality of terminals is greater than a predetermined value, the leased channel is assigned to the one of the plurality of terminals and data transferred from the one of the plurality of terminals is transferred using the leased channel.
According to another aspect of the invention, a packet transfer system for transferring data to a plurality of terminals while sectioning the data into given data-length packets, comprises:
a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly and a leased channel that only one of the plurality of terminals can use;
wherein only when the amount of data transferred to one of the plurality of terminals is greater than a predetermined value, the leased channel is assigned to the one of the plurality of terminals and data transferred to the one of the plurality of terminals is transferred using the leased channel.
According to another aspect of the invention, a packer transfer system for transferring data from a plurality of terminals while sectioning the data into given data-length packets, comprises:
a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly;
wherein the base station is composed of means for counting packet data transferred from the plurality of terminals, the counting means being provided for each of the plurality of terminals, a mode switching means for switching the shared channels into a shared mode that the plurality of terminals can use commonly or a leased mode that one of the plurality of terminals can use exclusively, the mode switching means being provided for each of the shared channels, and a control means for comparing a count value of the counting means with a predetermined value and controlling the operation of the mode switching means based on the comparison result, wherein the control means, when the count value of the counting means is greater than the predetermined value, controls the mode switching means to switch one of the shared channels into the leased mode that concerned one of the plurality of terminals can use exclusively.
According to another aspect of the invention, a packet transfer system for transferring data from a plurality of terminals while sectioning the data into given data-length packets, comprises:
a communication system that is composed of the plurality of terminals, a base station connected through a wireless line with the plurality of terminals and a switching office connected through one or more wired lines with the base station, the wired lines being composed of shared channels that the plurality of terminals can use commonly and a leased channel that only one of the plurality of terminals can use;
wherein the base station is composed of means for counting packet data transferred from the plurality of terminals, the counting mean; being provided for each of the plurality of terminals, and a control means for comparing a count value of the counting means with a predetermined value and controlling the setting of the wired lines to the plurality of terminals based on the comparison result, wherein the control means, when the count value of the counting means is greater than the predetermined value, controls the leased channel to be set to concerned one of the plurality of terminals.
In this invention, when data transferred from or to a terminal is greater than a predetermined value, one of shared channels is assigned exclusively to the terminal and data is transferred from or to the terminal using only the assigned channel.
Thus, in normal packet transferring, the communications are performed using by the shared channel with leased mode, and when specific-calling traffic increases, one of shared channels is switched into a leased mode that only the specific calling uses the channel. Since only the specific calling is transferred using the channel, packet data can be transferred efficiently without reducing the retransmission throughput of line and without increasing the hard physical quantity.
Alternatively, when data transferred from or to a terminal is greater than a predetermined value, a leased channel that one terminal can use exclusively is assigned to the terminal and data is transferred from or to the terminal using only the leased channel.
Thus, in normal packet transferring, the communications are performed using by the shared channel with leased mode, and when specific calling traffic increases, the leased channel is newly assigned to the specific calling. Since only the specific calling is transferred using the leased channel, packet data can be transferred efficiently without reducing the retransmission throughput of line and without increasing the hard physical quantity.